Investigation on Creep Behavior of Aggregates of Loess by a Discrete Element Method

In loess the aggregate is the basic structural unit, and its stability is an important factor affecting the composition, water stability and strength of loess. However, due to the difficulty of sample preparation, few scholars have done independent research on it. In this manuscript, a numerical model of aggregate is constructed by the discrete element method. Under the continuous action of certain stress, the uninterrupted development process of sample deformation with time was observed, that is, the creep of aggregate structures. The results show that the creep of aggregates is closely related to the relative movement, rotation and rearrangement of internal structural elements, and the most intuitive mesoscopic evolution of the adjustment process of structural elements is the change of contact number, namely the coordination number. The microscopic parameters and evolutionary characteristics of fabric can reveal the microscopic mechanism behind the macroscopic creep phenomenon. With the creep process, the creep stress is gradually borne by the normal contact force rather than the tangential contact force and has anisotropic characteristics. As a result of creep, the contact points of particles increase, and the interaction between aggregates changes from point contact to overlap contact. The constraint between aggregates increases, and the skeleton tends to be a more stable structure, which can bear a larger load.